Rubber composition for sealing material, and pneumatic tire

Abstract

The present invention provides a rubber composition for a sealant that exhibits excellent failure characteristics and good sealing properties even after aging, and a pneumatic tire (self-repairing tire) using the same. The rubber composition for a sealant comprises, per 100 parts by mass of butyl rubber, 0.5 to 3 parts by mass of a thiourea crosslinker, 1 to 10 parts by mass of a thiazole-based vulcanization accelerator and / or a thiuram-based vulcanization accelerator, and 100 to 300 parts by mass of a liquid polymer.

Description

Technical Field

[0001] The present invention relates to a rubber composition for a sealant material and a pneumatic tire using the same. Background Art

[0002] As a pneumatic tire with puncture resistance (hereinafter referred to as a "tire"), a self-repairing tire with a sealing material coated on the inner surface of the tire is known. A self-repairing tire automatically seals holes created by punctures with the sealing material, and various studies have been conducted on sealing materials.

[0003] Conventional sealing materials are cross-linked using organic peroxides such as peroxide (for example, Patent Document 1).

[0004] [Prior art literature]

[0005] [Patent Document]

[0006] [Patent Document 1] Japanese Patent No. 5589182 Summary of the Invention

[0007] [Problems to be Solved by the Invention]

[0008] However, the present inventors have discovered that conventional sealing materials cross-linked using organic peroxides such as peroxides have difficulty controlling the cross-linking reaction, resulting in a non-uniform cross-linking structure. Consequently, the required failure characteristics of these sealing materials remain to be improved. Furthermore, the present inventors have discovered that, because the cross-linking reaction using organic peroxides such as peroxides proceeds slowly, the cross-linking reaction does not complete even during storage or use after manufacture, leading to insufficient sealing properties due to aging.

[0009] The present invention solves the above-mentioned problems, and an object of the present invention is to provide a rubber composition for a sealant having excellent fracture characteristics and good sealing performance after aging degradation, and a pneumatic tire (self-repairing tire) using the same.

[0010] [Means for solving the problem]

[0011] The present invention relates to a rubber composition for a sealing material. The rubber composition comprises, per 100 parts by mass of a butyl rubber, 0.5 to 3 parts by mass of a thiourea crosslinking agent represented by the following formula (I), 1 to 10 parts by mass of a thiazole-based vulcanization accelerator and / or a thiuram-based vulcanization accelerator, and 100 to 300 parts by mass of a liquid polymer.

[0012]

[0013] (In formula (I), R 1 ~R 4are the same or different and represent a hydrogen atom or an alkyl group. 1 With R 3 , or R 1 With R 4 , or R 2 With R 3 , or R 2 With R 4 Can form a ring structure.)

[0014] Preferably, the thiourea cross-linking agent is any one of the following compounds.

[0015]

[0016]

[0017]

[0018]

[0019] Preferably, the liquid polymer is liquid polybutene.

[0020] Preferably, the liquid polymer has a kinematic viscosity of 500 to 6000 cSt measured at 100° C. according to ASTM D445.

[0021] Preferably, the content of the organic peroxide in the rubber composition for sealing material is 1 part by mass or less relative to 100 parts by mass of butyl rubber.

[0022] The present invention also relates to a pneumatic tire (self-repairing tire) having a sealing layer made using the rubber composition.

[0023] Preferably, the sealing layer has a complex elastic modulus G measured at 100°C according to ISO 13145. * It is 0.75~3.50kPa.

[0024] [Effects of the Invention]

[0025] The rubber composition for a sealant of the present invention contains, relative to 100 parts by mass of butyl rubber, 0.5 to 3 parts by mass of a thiourea crosslinking agent represented by the above formula (I), 1 to 10 parts by mass of a thiazole-based vulcanization accelerator and / or a thiuram-based vulcanization accelerator, and 100 to 300 parts by mass of a liquid polymer. Thus, it is possible to provide a rubber composition for a sealant having excellent fracture characteristics and good sealing properties after aging, and a pneumatic tire (self-repairing tire) using the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] [ Figure 1 ] Schematic illustration of an example of a coating device used in a method for manufacturing a self-repairing tire.

[0027] [ Figure 2 ]constitute Figure 1 An enlarged view of the vicinity of the front end of the nozzle of the coating device is shown.

[0028] [ Figure 3 ] Schematic illustration of the positional relationship of the nozzle relative to the tire.

[0029] [ Figure 4 ] A schematic illustration of an example of a state in which a roughly rope-shaped sealing material is continuously and spirally attached to the inner circumferential surface of a tire.

[0030] [ Figure 5 ]constitute Figure 1 An enlarged view of the vicinity of the front end of the nozzle of the coating device is shown.

[0031] [ Figure 6 ] Schematic illustration of an example of a sealing material attached to a self-repairing tire.

[0032] [ Figure 7 ] A schematic illustration of an example of a manufacturing device used in a method for manufacturing a self-repairing tire.

[0033] [ Figure 8 ] Cut at the straight line AA perpendicular to (orthogonal to) the coating direction (longitudinal direction) of the sealing material Figure 4 Schematic illustration of an example of a cross section of a sealing material when a sealing material is used.

[0034] [ Figure 9 ] Schematic illustration of an example of a cross section of a pneumatic tire.

[0035] [reference numerals]

[0036] 10 Tires

[0037] 11. Inner circumference of the tire

[0038] 14 Tread

[0039] 15 carcass

[0040] 16 Buffer layer (breaker)

[0041] 17 band

[0042] 20 Sealing material

[0043] 21 Width

[0044] 30 nozzles

[0045] 31 Tip of the nozzle

[0046] 40 Non-contact displacement sensor

[0047] 50 Rotary drive unit

[0048] 60 Twin-shaft compounding extruder

[0049] 61 (61a 61b 61c) Supply port

[0050] 62 Material Feeder

[0051] d, d0, d1, d2: The distance between the inner circumference of the tire and the front end of the nozzle DETAILED DESCRIPTION

[0052] The rubber composition for a sealant (sealant) of the present invention contains, per 100 parts by mass of butyl rubber, 0.5 to 3 parts by mass of a thiourea crosslinking agent represented by formula (I), 1 to 10 parts by mass of a thiazole-based vulcanization accelerator and / or a thiuram-based vulcanization accelerator, and 100 to 300 parts by mass of a liquid polymer. This composition exhibits excellent initial failure characteristics and good sealing performance even after aging. Furthermore, changes in failure characteristics over time can be suppressed.

[0053] The rubber composition can achieve the above-mentioned effects. Although the reason for achieving such effects is not entirely clear, it can be inferred as follows.

[0054] For butyl rubber, the use of a thiourea crosslinking agent represented by the above formula (I) as an alternative to organic peroxides such as peroxide, and further use of a thiazole-based vulcanization accelerator and / or a thiuram-based vulcanization accelerator, ensures excellent tear properties, furthermore, provides excellent sealing properties after aging degradation, and suppresses temporal changes in tear properties. This is believed to be because, in this crosslinking system, the control of the crosslinking reaction is simplified, and the crosslinked structure easily becomes uniform, thereby ensuring excellent tear properties. Furthermore, because the crosslinking reaction proceeds rapidly and is completed rather than slowly, it provides excellent sealing properties after aging degradation, and suppresses temporal changes in tear properties.

[0055] Then, by adding the above-mentioned specific amount of liquid polymer to the butyl rubber, the above-mentioned specific amount of thiourea crosslinking agent represented by the above formula (I) and the above-mentioned specific amount of thiazole-based vulcanization accelerator and / or thiuram-based vulcanization accelerator can be more uniformly dispersed in the composition, making the crosslinking structure more uniform, thereby achieving good fracture resistance, and further, achieving good sealing performance after aging, while suppressing the change in fracture resistance over time.

[0056] That is, in the above composition, due to the synergistic effect of the above-mentioned specific amount of the thiourea crosslinking agent represented by the above formula (I), the above-mentioned specific amount of the thiazole-based vulcanization accelerator and / or the thiuram-based vulcanization accelerator, and the above-mentioned specific amount of the liquid polymer, the composition exhibits excellent breaking properties, has good sealing properties after aging, and can also suppress the change in breaking properties over time.

[0057] The rubber composition for sealant (sealant) of the present invention is suitable for use in areas of the inner surface of a self-repairing tire, such as the tread, where puncture is possible. The sealant will be described below along with a preferred example of a method for manufacturing a self-repairing tire.

[0058] A self-repairing tire can be manufactured, for example, by mixing the components that constitute a sealing material to prepare the sealing material, and then applying the resulting sealing material to the inner circumference of the tire by coating or other means to form a sealing layer. This self-repairing tire has a sealing layer located radially inward of the inner liner.

[0059] A preferred example of a method for producing a self-repairing tire will be described below.

[0060] A self-repairing tire can be manufactured, for example, by mixing the components that constitute a sealing material to prepare the sealing material, and then applying the resulting sealing material to the inner circumference of the tire by coating or other means to form a sealing layer. This self-repairing tire has a sealing layer located radially inward of the inner liner.

[0061] As sealing material, as long as it is a sealing material with adhesiveness, there is no particular limitation, and the rubber composition commonly used in the puncture seal of tire can be used. As the rubber component constituting the main component of the rubber composition, butyl rubber can be used. Thus, there is the following tendency: while ensuring good air permeability and resistance to degradation, appropriate fluidity is obtained. As butyl rubber, in addition to butyl rubber (IIR), halogenated butyl rubbers (X-IIR) such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR) can also be enumerated. These can be used alone, or two or more can be used. Wherein, based on the reason that halogenated butyl rubber is easier to carry out cross-linking reaction, easier to improve cross-linking density, and can obtain better effect than unhalogenated butyl rubber, halogenated butyl rubber is preferred, and the reason that the promotion effect based on cross-linking reaction is higher and can obtain better effect is more preferred brominated butyl rubber.

[0062] From the perspective of ensuring better fluidity of the sealing material, the butyl rubber preferably has a Mooney viscosity (ML1+8) at 125°C of 20 or greater, more preferably 40 or greater, and preferably 60 or less. When the Mooney viscosity is within the above range, better effects tend to be achieved.

[0063] The Mooney viscosity ML1+8 at 125° C. was measured in accordance with JIS K-6300-1:2001 at a test temperature of 125° C. with an L-shaped rotor having a residual heat time of 1 minute and a rotor rotation time of 8 minutes.

[0064] The halogen content of the halogenated butyl rubber is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and preferably 5.0% by mass or less, more preferably 4.0% by mass or less. This tends to promote a better crosslinking reaction and achieve better results.

[0065] The halogen content can be measured by solution NMR.

[0066] As commercially available products of the butyl rubber, for example, products from ExxonMobil Corporation, Nippon Butyl Co., Ltd., JSR Corporation, Cenway Corporation, and the like can be used.

[0067] The content of the butyl rubber in 100% by mass of the rubber component is preferably 80% by mass or more, more preferably 90% by mass or more, and can be 100% by mass. When the content is within the above range, better effects tend to be obtained.

[0068] In addition to the above-mentioned rubber components, other components such as diene rubbers such as natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR) may be used in combination as the rubber component. These may be used alone or in combination of two or more.

[0069] As a rubber component, for example, a rubber component containing at least one functional group with metal coordination ability in its molecular structure can be suitably used. Here, as a functional group with metal coordination ability, as long as it is a functional group with metal coordination ability, there is no particular limitation, and examples thereof include functional groups containing metal-coordinating atoms such as oxygen, nitrogen, and sulfur. Specifically, dithiocarbamate groups, phosphoric acid groups, carboxylic acid groups, carbamate groups, dithiocarboxylic acid groups, aminophosphoric acid groups, thiol groups, etc. can be exemplified. The above-mentioned functional groups can contain only one type, or can contain two or more types.

[0070] In addition, examples of the coordination metal for the functional group include Fe, Cu, Ag, Co, Mn, Ni, Ti, V, Zn, Mo, W, Os, Mg, Ca, Sr, Ba, Al, and Si. For example, in a polymer material containing a functional group (-COO, etc.) having a metal coordination ability and to which a compound having such a metal atom (M1) is added, each -COOM1 is coordinated and bonded, and multiple -COOM1s overlap to form a cluster of metal atoms. In addition, the amount of the metal atom (M1) added is preferably 0.01 to 200 parts by mass relative to 100 parts by mass of the rubber component.

[0071] As commercially available products of the rubber component, for example, products from Sumitomo Chemical Co., Ltd., Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used.

[0072] The sealing material contains a liquid polymer. This ensures optimal fluidity. As described above, by adding the specific amount of liquid polymer to the butyl rubber, the specific amount of thiourea crosslinking agent represented by formula (I) and the specific amount of thiazole vulcanization accelerator and / or thiuram vulcanization accelerator can be more evenly dispersed in the composition, resulting in excellent failure characteristics, good sealing performance after aging, and suppressed changes in failure characteristics over time.

[0073] As the liquid polymer in the sealing material, liquid polybutene, liquid polyisobutylene, liquid polyisoprene, liquid polybutadiene, liquid polyα-olefin, liquid isobutylene, liquid ethylene / α-olefin copolymer, liquid ethylene / propylene copolymer, liquid ethylene / butylene copolymer, etc. can be mentioned. Among them, liquid polybutene is preferred because of its high compatibility with butyl rubber and the ability to achieve better results. As the liquid polybutene, copolymers with a molecular structure of long-chain hydrocarbons obtained by further reacting n-butene with isobutylene as the main body can be mentioned, and hydrogenated liquid polybutene can also be used. As the liquid polymer, only one type can be used, or two or more types can be used in combination.

[0074] The kinematic viscosity of liquid polymers such as liquid polybutene at 100°C is preferably 500 cSt or higher, more preferably 580 cSt or higher, and even more preferably 3000 cSt or higher. The kinematic viscosity at 100°C is preferably 6000 cSt or lower, more preferably 5500 cSt or lower, and even more preferably 5000 cSt or lower. When the kinematic viscosity is within this range, better effects tend to be achieved.

[0075] The kinematic viscosity of liquid polymers such as liquid polybutene at 40°C is preferably 15,000 cSt or higher, more preferably 20,000 cSt or higher, even more preferably 25,000 cSt or higher, particularly preferably 50,000 cSt or higher, and most preferably 100,000 cSt or higher. The kinematic viscosity at 40°C is preferably 250,000 cSt or lower, more preferably 200,000 cSt or lower, and even more preferably 180,000 cSt or lower. When the kinematic viscosity is within this range, better effects tend to be achieved.

[0076] In addition, the kinematic viscosity is a value measured at 40°C or 100°C in accordance with ASTM D445 (2019).

[0077] As commercially available products of the liquid polymer, for example, products from JXTG Energy Corporation, NOF Corporation, DAELIM, KEMAT, INEOS, and the like can be used.

[0078] Relative to 100 parts by mass of butyl rubber, the content of liquid polymer is more than 100 parts by mass, more preferably more than 120 parts by mass, further preferably more than 140 parts by mass, particularly preferably more than 160 parts by mass, and most preferably more than 180 parts by mass. This content is less than 300 parts by mass, more preferably less than 280 parts by mass, further preferably less than 260 parts by mass, particularly preferably less than 240 parts by mass, and most preferably less than 220 parts by mass. When this content is within the above range, there is a tendency to obtain better results. When the content of liquid polymer is less than 100 parts by mass, the sealing performance after years of degradation cannot be guaranteed. When this content is more than 300 parts by mass, the damage characteristics are low due to being too soft, and in addition, the shape of the sealing material cannot be maintained.

[0079] It is preferred to use only one liquid polymer (preferably liquid polybutene) having a kinematic viscosity at 100°C and a kinematic viscosity at 40°C within the above ranges at the above content as the liquid polymer. Using such a liquid polymer at such a content can achieve better effects.

[0080] As the crosslinking agent, a thiourea crosslinking agent represented by the following formula (I) is used. These can be used alone or in combination of two or more.

[0081]

[0082] (In formula (I), R 1 ~R 4 are the same or different and represent a hydrogen atom or an alkyl group. 1 With R 3 , or R 1 With R 4 , or R 2 With R3 , or R 2 With R 4 Can form a ring structure.)

[0083] As R 1 ~R 4 The alkyl group is not particularly limited and may be branched or unbranched. Examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, 2-ethylhexyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, and octadecyl. These may be used alone or in combination of two or more. Among these, methyl, ethyl, n-propyl, and isopropyl are preferred, and methyl and ethyl are more preferred.

[0084] R 1 ~R 4 The number of carbon atoms in the alkyl group is preferably 1 or more, and is preferably 30 or less, more preferably 20 or less, further preferably 10 or less, particularly preferably 5 or less, most preferably 3 or less, and most preferably 2 or less. When the number of carbon atoms is within the above range, there is a tendency that better effects can be obtained.

[0085] Based on the reason that better effect can be obtained, as R 1 ~R 4 , preferably at least one is an alkyl group, preferably at least two are alkyl groups. 1 ~R 4 All of R may be alkyl groups, but preferably, at least one of them is a hydrogen atom, that is, R 1 ~R 4 The number of alkyl groups is less than 3.

[0086] In addition, based on the reason that a better effect can be obtained, preferably, R 1 and R 2 At least one of them is an alkyl group, and R 3 and R 4 At least one of them is an alkyl group.

[0087] Examples of the compound represented by the above formula (I) include N,N'-dimethylthiourea, N,N'-diethylthiourea (compound represented by the following formula (1)), N,N'-dipropylthiourea, N,N'-dibutylthiourea (compound represented by the following formula (4)), N,N'-dipentylthiourea, N,N'-methylethylthiourea, N,N'-methylpropylthiourea, N,N'-methylbutylthiourea, N,N'-ethylpropylthiourea, N,N'-ethylbutylthiourea, trimethylthiourea (compound represented by the following formula (2)), triethylthiourea, tripropylthiourea, tributylthiourea, tripentylthiourea, a compound represented by the following formula (3), tetramethylthiourea, tetraethylthiourea, tetrapropylthiourea, tetrabutylthiourea, and tetrapentylthiourea. These may be used alone or in combination of two or more. Among them, N,N'-diethylthiourea (a compound represented by the following formula (1)), trimethylthiourea (a compound represented by the following formula (2)), a compound represented by the following formula (3), and N,N'-dibutylthiourea (a compound represented by the following formula (4)) are preferred because better effects can be obtained. N,N'-diethylthiourea (a compound represented by the following formula (1)) and trimethylthiourea (a compound represented by the following formula (2)) are more preferred.

[0088]

[0089]

[0090]

[0091]

[0092] As commercially available products of the thiourea cross-linking agent, for example, products from Sanshin Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Nocceler TMU, Nocceler EUR, and the like can be used.

[0093] Relative to 100 parts by mass of butyl rubber, the content of the thiourea crosslinking agent represented by formula (I) is more than 0.5 parts by mass, preferably more than 0.7 parts by mass, more preferably more than 0.9 parts by mass, further preferably more than 1.1 parts by mass, particularly preferably more than 1.3 parts by mass. This content is below 3 parts by mass, preferably below 2.5 parts by mass, more preferably below 2 parts by mass, further preferably below 1.8 parts by mass. When this content is within the above range, there is a tendency to obtain better effects. When the content of thiourea crosslinking agent is less than 0.5 parts by mass, the crosslinking reaction can not be fully carried out and is too soft, so the destruction characteristics are low. In addition, the shape of the sealing material cannot be maintained. When this content is more than 3 parts by mass, the sealing performance after years of deterioration cannot be guaranteed.

[0094] As the cross-linking agent, it is preferred not to use conventionally used organic peroxides, sulfur, and the like.

[0095] Examples of the organic peroxide include acyl peroxides such as benzoyl peroxide, dibenzoyl peroxide, and p-chlorobenzoyl peroxide; peroxyesters such as 1-butyl peroxyacetate, t-butyl peroxybenzoate, and t-butyl peroxyphthalate; ketone peroxides such as methyl ethyl ketone peroxide; alkyl peroxides such as di-t-butyl peroxybenzoate and 1,3-bis(1-butylperoxyisopropyl)benzene; hydroperoxides such as t-butyl peroxide (t-butyl hydroperoxide); diisopropylbenzene peroxide; and t-butylisopropylbenzene peroxide.

[0096] As commercially available products of the organic peroxide, for example, products from NOF Corporation, Arkema, Kawaguchi Pharmaceutical Co., Ltd., Nouryon, etc. can be used.

[0097] The content of the organic peroxide per 100 parts by mass of the butyl rubber is preferably 1 part by mass or less, more preferably 0.5 part by mass or less, even more preferably 0.1 part by mass or less, particularly preferably 0.01 part by mass or less, and most preferably 0 part by mass. When the content is within the above range, better effects tend to be achieved.

[0098] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur.

[0099] As commercially available sulfur products, for example, products from Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., FLEXIS Co., Ltd., Nippon Senryu Industry Co., Ltd., Hosoi Chemical Co., Ltd., and the like can be used.

[0100] The sulfur content per 100 parts by mass of the butyl rubber is preferably 1 part by mass or less, more preferably 0.5 part by mass or less, even more preferably 0.1 part by mass or less, particularly preferably 0.01 part by mass or less, and most preferably 0 part by mass. When the sulfur content is within the above range, better effects tend to be achieved.

[0101] Here, the sulfur content refers to the amount of sulfur derived from pure sulfur components such as powdered sulfur, and does not include sulfur derived from sulfur-containing compounds such as phenol-sulfur chloride condensate.

[0102] As a crosslinking aid (vulcanization accelerator), a thiazole-based vulcanization accelerator and / or a thiuram-based vulcanization accelerator are used. These may be used alone or in combination of two or more.

[0103] Examples of thiazole vulcanization accelerators include 2-mercaptobenzothiazole (MBT), sodium salts, zinc salts, copper salts, and cyclohexylamine salts of 2-mercaptobenzothiazole, dibenzothiazolyl disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-diethyl-4-morpholinothio)benzothiazole, and 2-(4'-morpholinodithio)benzothiazole. These can be used alone or in combination of two or more. Among these, dibenzothiazolyl disulfide (MBTS) and 2-mercaptobenzothiazole (MBT) are preferred, with dibenzothiazolyl disulfide (MBTS) being more preferred, due to their ability to achieve better results.

[0104] Examples of thiuram-based vulcanization accelerators include tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N), tetramethylthiuram monosulfide, dipentamethylenethiuram tetrasulfide, tetrabutylthiuram disulfide, and tetraethylthiuram disulfide. These can be used alone or in combination of two or more. Among these, tetrabenzylthiuram disulfide (TBzTD) and tetramethylthiuram disulfide (TMTD) are preferred, and tetrabenzylthiuram disulfide (TBzTD) is more preferred because they can provide better effects.

[0105] As commercially available products of the cross-linking auxiliary agent (vulcanization accelerator), for example, products of Ouchi Shinko Chemical Co., Ltd., Kawaguchi Chemical Industry Co., Ltd., Sanshin Chemical Co., Ltd., LANXESS Co., Ltd., and the like can be used.

[0106] Relative to 100 parts by mass of butyl rubber, the content of thiazole-based vulcanization accelerator and / or thiuram-based vulcanization accelerator is 1 part by mass or more, more preferably 2 parts by mass or more, further preferably 3 parts by mass or more, particularly preferably 4 parts by mass or more. This content is 10 parts by mass or less, more preferably 8 parts by mass or less, further preferably 7 parts by mass or less, particularly preferably 6 parts by mass or less. When this content is within the above range, there is a tendency to obtain better results. When the content of the above-mentioned vulcanization accelerator is less than 1 part by mass, the cross-linking promoting effect cannot be fully exerted, the cross-linking reaction cannot be rapidly carried out and completed, and the sealing performance after years of degradation cannot be guaranteed. When this content is more than 10 parts by mass, the cross-linking promoting effect is too strong, and therefore the sealing performance after years of degradation cannot be guaranteed.

[0107] Here, the content of the thiazole vulcanization accelerator and / or the thiuram vulcanization accelerator refers to the individual content when the thiazole vulcanization accelerator or the thiuram vulcanization accelerator is used alone, and the total content when two or more types, such as a thiazole vulcanization accelerator and a thiuram vulcanization accelerator, are used in combination.

[0108] It is preferred not to use a quinone dioxime compound (quinoid compound) which is a conventional cross-linking auxiliary agent (vulcanization accelerator).

[0109] Examples of the quinone dioxime compound include p-benzoquinone dioxime, p-quinone dioxime, p-quinone dioxime diacetate, p-quinone dioxime dicaproate, p-quinone dioxime dilaurate, p-quinone dioxime distearate, p-quinone dioxime dicrotonate, p-quinone dioxime dicycloalkanoate, p-quinone dioxime succinate, p-quinone dioxime adipate, p-quinone dioxime difuroate (p-quinone dioxime), and p-quinone dioxime succinate. dioximedifuroate), p-quinonedioxime dibenzoate, p-quinonedioxime bis(o-chlorobenzoate), p-quinonedioxime bis(p-chlorobenzoate), p-quinonedioxime bis(p-nitrobenzoate), p-quinonedioxime bis(m-nitrobenzoate), p-quinonedioxime bis(3,5-dinitrobenzoate), p-quinonedioxime bis(p-methoxybenzoate), p-quinonedioxime bis(n-pentyloxybenzoate), p-quinonedioxime bis(m-bromobenzoate), etc.

[0110] As commercially available products of the quinone dioxime compound, for example, products from Fujifilm Wako Pure Chemical Industries, Ltd., Junsei Chemical Co., Ltd., LORD Corporation, and the like can be used.

[0111] The content of the quinone dioxime compound per 100 parts by mass of the butyl rubber is preferably 1 part by mass or less, more preferably 0.5 part by mass or less, even more preferably 0.1 part by mass or less, particularly preferably 0.01 part by mass or less, and most preferably 0 part by mass. When the content is within the above range, better effects tend to be achieved.

[0112] The above composition preferably contains zinc oxide.

[0113] Examples of zinc oxide include conventionally known zinc oxides, and commercially available products include those from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Shodo Chemical Industry Co., Ltd., and Sakai Chemical Industry Co., Ltd. These may be used alone or in combination of two or more.

[0114] The zinc oxide content per 100 parts by mass of the butyl rubber is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0115] The rubber composition may contain inorganic fillers such as carbon black, silica, barium sulfate, talc, mica, mM2·xSiOy·zH2O (wherein M2 represents at least one metal selected from aluminum, calcium, magnesium, titanium, and zirconium, or an oxide, hydroxide, hydrate, or carbonate of such metal; m represents a value in the range of 1 to 5, x represents a value in the range of 0 to 10, y represents a value in the range of 2 to 5, and z represents a value in the range of 0 to 10); and plasticizers such as aromatic process oils, naphthenic process oils, and paraffinic process oils. These may be used alone or in combination of two or more.

[0116] Specific examples of the filler represented by mM2·xSiOy·zH2O include aluminum hydroxide (Al(OH)3), aluminum oxide (Al2O3, Al2O3·3H2O (hydrate)), clay (Al2O3·2SiO2), kaolin (Al2O3·2SiO2·2H2O), pyrophyllite (Al2O3·4SiO2·H2O), bentonite (Al2O3·4SiO2·2H2O), aluminum silicate (Al2SiO5, Al4(SiO2)3·5H2O), and so on. Calcium silicate (Ca2SiO4), calcium magnesium silicate (CaMgSiO4), magnesium hydroxide (Mg(OH)2), magnesium oxide (MgO), talc (MgO·4SiO2·H2O), attapulgite (5MgO·8SiO2·9H2O), magnesium aluminum oxide (MgO·Al2O3), titanium dioxide (TiO2), titanium black (Ti n O 2n-1 ) etc. These may be used alone or in combination of two or more.

[0117] As commercially available products of the above-mentioned inorganic filler, for example, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nichia Carbon Co., Ltd., Columbia Carbon Co., Ltd., Degussa Co., Ltd., Rhodia Co., Ltd., Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Co., Ltd., etc. can be used.

[0118] As commercially available products of the above-mentioned plasticizers, for example, products of Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Nippon Energy Co., Ltd., Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Manufacturing Co., Ltd., Showa Shell Sekiyu Co., Ltd., Fuji Kosan Co., Ltd., Nissin Oilio Group Co., Ltd., and Taoka Chemical Industry Co., Ltd. can be used.

[0119] The content of the inorganic filler per 100 parts by mass of the butyl rubber is preferably 1 part by mass or greater, more preferably 10 parts by mass or greater, and even more preferably 20 parts by mass or greater. This content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less. When this content is within this range, better effects tend to be achieved.

[0120] Carbon black is a preferred inorganic filler for preventing degradation due to ultraviolet rays and ensuring adequate reinforcement while maintaining good elongation at break. The carbon black content is preferably 1 part by mass or greater, more preferably 10 parts by mass or greater, and even more preferably 20 parts by mass or greater, per 100 parts by mass of butyl rubber. This content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less. When this content is within the above range, better results tend to be achieved.

[0121] Carbon black commonly used for rubber can be appropriately used. Specifically, N110, N115, N120, N121, N125, N134, N135, N219, N220, N231, N234, N293, N299, N326, N330, N335, N339, N343, N347, N351, N356, N358, N375, N539, N550, N582, N630, N642, N650, N660, N683, N754, N762, N765, N772, N774, N787, N907, N908, N990, and N991 can be suitably used. In addition, our company's own synthetic products can also be suitably used. These may be used alone or in combination of two or more.

[0122] As the plasticizer (oil), dioctyl phthalate (DOP) is preferred because a plasticizer with a low softening point is preferred in order to maintain a softened state at low temperatures.

[0123] In this specification, the plasticizer does not include the above-mentioned liquid polymer.

[0124] The content of the plasticizer is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, relative to 100 parts by mass of the butyl rubber, and is preferably 40 parts by mass or less, more preferably 30 parts by mass or less.

[0125] In addition to the above components, the rubber composition may further contain additives commonly used in the tire industry, such as silane coupling agents, various antioxidants, etc. The content of these additives is preferably 0.1 to 200 parts by mass per 100 parts by mass of the butyl rubber.

[0126] The rubber composition for a sealant (sealant) is preferably one prepared by mixing a butyl rubber, a specific amount of a thiourea crosslinking agent represented by the above formula (I), a specific amount of a thiazole vulcanization accelerator and / or a thiuram vulcanization accelerator, and a specific amount of a liquid polymer. More preferably, it is one prepared by mixing a butyl rubber, a specific amount of a thiourea crosslinking agent represented by the above formula (I), a specific amount of a thiazole vulcanization accelerator and / or a thiuram vulcanization accelerator, and a specific amount of polybutene.

[0127] By mixing the above materials to prepare a sealing material, and applying the prepared sealing material to the inner circumference of the tire (preferably to the inner liner layer in the radial direction of the tire), a self-repairing tire having a sealing layer in the radial direction of the tire inner liner can be manufactured. However, the mixing of the various materials constituting the sealing material can be carried out using, for example, a well-known mixer. An example of a manufacturing device used in the method for manufacturing a self-repairing tire is Figure 7 shown.

[0128] The inner circumference of the tire can be coated with a sealant only on the portion of the tire corresponding to the tread, more preferably, only on the portion of the tire corresponding to the breaker. By omitting the application of sealant to portions not requiring application, self-repairing tires can be manufactured with improved productivity.

[0129] Here, the inner circumference of the tire corresponding to the tread portion refers to the inner circumference of the tire located radially inward of the tread portion that contacts the road surface, and the inner circumference of the tire corresponding to the buffer layer refers to the inner circumference of the tire located radially inward of the buffer layer. In addition, the buffer layer refers to a component that is arranged inside the tread and located radially outward of the carcass, specifically, Figure 9 The buffer layer 16 and other components shown.

[0130] Typically, unvulcanized tires are vulcanized using a bladder. This bladder expands during vulcanization, coming into close contact with the tire's inner circumference (inner liner). Therefore, at the end of vulcanization, a release agent is typically applied to the tire's inner circumference (inner liner) to prevent adhesion between the bladder and the tire.

[0131] As a release agent, a water-soluble coating or a release rubber is generally used. However, when a release agent is present on the inner circumference of the tire, there is a concern that the adhesion between the sealing material and the inner circumference of the tire will decrease. Therefore, it is preferable to pre-remove the release agent from the inner circumference of the tire. In particular, it is more preferable to pre-remove the release agent from at least the portion of the inner circumference of the tire where the sealing material is initially applied. In addition, it is further preferable to pre-remove the release agent from all portions of the inner circumference of the tire where the sealing material is applied. This further improves the adhesion of the sealing material to the inner circumference of the tire, making it possible to manufacture a self-repairing tire with even higher sealing performance.

[0132] The method for removing the release agent from the inner circumferential surface of the tire is not particularly limited, and examples thereof include known methods such as buffing, laser treatment, high-pressure water washing, and removal with a detergent (preferably a neutral detergent).

[0133] By continuously and spirally applying the sealing material to the inner circumference of the tire, deterioration of the tire's uniformity can be prevented, allowing the manufacture of a self-repairing tire with excellent weight balance. Furthermore, by continuously and spirally applying the sealing material to the inner circumference of the tire, a uniform sealing layer of the sealing material can be formed in the tire's circumferential direction and in the tire's width direction (particularly in the tire's circumferential direction), thereby enabling the stable and productive manufacture of self-repairing tires with excellent sealing properties. Furthermore, the sealing material is preferably applied without overlapping in the width direction, and more preferably applied seamlessly. This further prevents deterioration of the tire's uniformity while forming a more uniform sealing layer.

[0134] Furthermore, raw materials are sequentially fed into a continuous kneading machine (particularly a twin-screw kneading extruder), whereupon the sealing material is sequentially prepared. The prepared sealing material is continuously discharged from a nozzle connected to the discharge port of the continuous kneading machine (particularly a twin-screw kneading extruder), and the sealing material is sequentially directly applied to the inner circumference of the tire. This allows for the production of self-repairing tires with high productivity.

[0135] The sealing layer is preferably formed by continuously and spirally applying a substantially cord-shaped sealing material to the inner circumferential surface of the tire. This allows a sealing layer to be formed on the inner circumferential surface of the tire, comprising a substantially cord-shaped sealing material continuously and spirally disposed along the inner circumferential surface of the tire. The sealing layer can be formed by stacking sealing materials, but is preferably formed from a single layer of sealing material.

[0136] When the sealing material is in a roughly cord-like shape, a single-layer sealing layer can be formed by continuously applying the sealing material in a spiral pattern to the inner circumference of the tire. Since the applied sealing material has a certain thickness when the sealing material is in a roughly cord-like shape, even a single-layer sealing layer can prevent degradation of tire uniformity, enabling the production of self-repairing tires with excellent weight balance and sealing properties. Furthermore, since only a single layer of sealing material is applied without laminating any additional layers of sealing material, self-repairing tires can be manufactured with improved productivity.

[0137] The number of times the sealing material is wound around the inner circumference of the tire is preferably 20 times or more, more preferably 35 times or more, and preferably 70 times or less, more preferably 60 times or less, and further preferably 50 times or less, in order to prevent deterioration of tire uniformity and to produce a self-repairing tire with excellent weight balance and good sealing performance with better productivity. Here, the number of windings 2 times means that the sealing material is applied to the inner circumference of the tire twice. Figure 4 The sealing material is wound 6 times.

[0138] Next, a method of applying the sealant to the inner peripheral surface of the tire will be described below.

[0139] <First embodiment>

[0140] In a first embodiment, a self-repairing tire can be manufactured by the following steps: Step (1): while rotating the tire and moving at least one of the tire and the nozzle in the width direction of the tire, an adhesive sealing material is applied to the inner circumferential surface of the tire through the nozzle, and the distance between the inner circumferential surface of the tire and the front end of the nozzle is measured by a non-contact displacement sensor; Step (2): based on the measurement result, by moving at least one of the tire and the nozzle in the radial direction of the tire, the interval between the inner circumferential surface of the tire and the front end of the nozzle is adjusted to a specified distance; Step (3): applying the sealing material to the inner circumferential surface of the tire with the adjusted interval.

[0141] By using a non-contact displacement sensor to measure the distance between the tire's inner circumference and the nozzle tip and providing feedback on the measurement results, the gap between the tire's inner circumference and the nozzle tip can be maintained at a constant distance. Furthermore, since the sealant is applied to the tire's inner circumference while maintaining this constant distance, the sealant's thickness can be uniform, regardless of variations in tire shape or unevenness in the joint. Furthermore, since there's no need to input coordinate values ​​for each tire size, as is conventionally done, sealant application can be highly efficient.

[0142] Figure 1This is a schematic diagram illustrating an example of a coating device used in a method for manufacturing a self-repairing tire. Figure 2 It is composed Figure 1 An enlarged view of the coating apparatus near the nozzle front end is shown.

[0143] Figure 1 Shown is a cross section of a portion of the tire 10 cut along the meridian direction (a cross section cut on a plane including the tire width direction and the radial direction). Figure 2 Shown is a cross section of a portion of the tire 10 cut along a plane including the circumferential and radial directions of the tire. Figure 1 and Figure 2 , the X direction is the width direction (axial direction) of the tire, the Y direction is the circumferential direction of the tire, and the Z direction is the radial direction of the tire.

[0144] The tire 10 is mounted on a rotation drive device (not shown) that allows the tire to rotate while being fixed and simultaneously move in the width direction and radial direction of the tire. The rotation drive device can independently rotate the tire about its axis, move the tire in the width direction, and move the tire in the radial direction.

[0145] Furthermore, the rotation drive device includes a control mechanism (not shown) that can control the radial movement of the tire. The control mechanism can control the width movement of the tire and / or the rotation speed of the tire.

[0146] The nozzle 30 is mounted on the front end of an extruder (not shown) and can be inserted into the inner side of the tire 10. The adhesive sealing material 20 extruded from the extruder is discharged from the front end 31 of the nozzle 30.

[0147] The non-contact displacement sensor 40 is attached to the nozzle 30 and measures the distance d between the inner circumferential surface 11 of the tire 10 and the front end 31 of the nozzle 30 .

[0148] As described above, the distance d measured by the non-contact displacement sensor is the distance between the inner peripheral surface of the tire and the tip of the nozzle in the radial direction of the tire.

[0149] In the method for manufacturing a self-repairing tire of this embodiment, first, the tire 10 formed in the vulcanization process is mounted on a rotation drive device, and the nozzle 30 is inserted into the inner side of the tire 10. Then, as shown in FIG. Figure 1 and Figure 2 As shown, while the tire 10 is rotated and moved in the width direction, the sealing material 20 is discharged from the nozzle 30 and continuously applied to the inner circumferential surface 11 of the tire 10. The movement of the tire 10 in the width direction is performed along the contour shape of the inner circumferential surface 11 of the tire 10 that has been input in advance.

[0150] As described later, the sealing material 20 is preferably in a roughly rope-shaped shape. More specifically, when the sealing material is applied to the inner circumference of the tire, the sealing material is preferably kept in a roughly rope-shaped shape. At this time, the roughly rope-shaped sealing material 20 can be continuously spirally attached to the inner circumference 11 of the tire 10.

[0151] In this specification, the term "substantially rope-shaped" means a shape having a length longer than a width and a certain degree of width and thickness. Figure 4 The figure schematically shows an example of a state in which a substantially rope-shaped sealing material is continuously and spirally attached to the inner circumference of a tire. Figure 8 Schematically shows the Figure 4 An example of a cross section of a sealing material when the sealing material is cut along a straight line AA perpendicular to the coating direction (length direction) of the sealing material. In this way, the substantially rope-shaped sealing material has a certain width ( Figure 8 length shown in W) and a certain degree of thickness ( Figure 8 Here, the width of the sealing material refers to the width of the sealing material after coating, and the thickness of the sealing material refers to the thickness of the sealing material after coating, more specifically, the thickness of the sealing layer.

[0152] The substantially rope-shaped sealing material specifically satisfies the thickness of the sealing material described below (thickness of the sealing material after coating, thickness of the sealing layer, Figure 8 The preferred numerical range of the length shown by D in FIG), and the width of the sealing material (the width of the sealing material after coating, Figure 4 The length shown by W, Figure 6 The sealing material preferably meets the preferred numerical range of the ratio of the thickness of the sealing material to the width of the sealing material (the thickness of the sealing material / the width of the sealing material) described below. In addition, the sealing material also meets the preferred numerical range of the cross-sectional area of ​​the sealing material described below.

[0153] In the method for manufacturing a self-repairing tire according to the present embodiment, a sealant is applied to the inner peripheral surface of the tire through the following steps (1) to (3).

[0154] <Process (1)>

[0155] like Figure 2 As shown, the distance d between the inner circumferential surface 11 of the tire 10 and the front end 31 of the nozzle 30 before the sealing material 20 is applied is measured by the non-contact displacement sensor 40. The distance d is measured each time the sealing material 20 is applied to the inner circumferential surface 11 of each tire 10, from the start to the end of the application of the sealing material 20.

[0156] <Process (2)>

[0157] The measured data of the distance d is transmitted to the control mechanism of the rotation drive device. The control mechanism adjusts the radial movement of the tire based on the measured data so that the distance between the inner circumference 11 of the tire 10 and the tip 31 of the nozzle 30 becomes a predetermined distance.

[0158] <Process (3)>

[0159] The sealing material 20 is continuously discharged from the front end 31 of the nozzle 30 and is applied to the inner circumferential surface 11 of the tire 10 at the adjusted intervals. By the above steps (1) to (3), the sealing material 20 can be applied to the inner circumferential surface 11 of the tire 10 with a uniform thickness.

[0160] Figure 3 This is a schematic diagram illustrating the positional relationship of the nozzle relative to the tire.

[0161] like Figure 3 As shown, the sealing material can be applied while the distance between the inner circumferential surface 11 of the tire 10 and the front end 31 of the nozzle 30 is maintained at a predetermined distance d0 while the nozzle 30 moves to the positions shown in (a) to (d) relative to the tire 10.

[0162] For the purpose of obtaining a better effect, the adjusted interval d0 is preferably 0.3 mm or more, more preferably 1.0 mm or more. Furthermore, the adjusted interval d0 is preferably 3.0 mm or less, more preferably 2.0 mm or less.

[0163] Here, the adjusted interval d0 refers to the distance in the tire radial direction between the tire inner peripheral surface and the nozzle tip adjusted in the above step (2).

[0164] In addition, based on the reason that better effects can be obtained, the adjusted interval d0 is preferably less than 30% of the thickness of the applied sealing material, more preferably less than 20%, and further preferably more than 5% of the thickness of the applied sealing material, more preferably more than 10%.

[0165] Based on the reason that better effect can be obtained, the thickness of the sealing material (the thickness of the sealing material after coating, the thickness of the sealing layer, Figure 8The length (denoted by D) is not particularly limited, but is preferably 1.0 mm or greater, more preferably 1.5 mm or greater, even more preferably 2.0 mm or greater, and particularly preferably 2.5 mm or greater, for the sake of achieving better results. Furthermore, it is preferably 10 mm or less, more preferably 8.0 mm or less, and even more preferably 5.0 mm or less. The thickness of the sealing material can be adjusted by adjusting the tire's rotational speed, the tire's widthwise movement speed, the distance between the nozzle tip and the tire's inner circumference, and other factors.

[0166] The thickness of the sealing material (thickness of the sealing material after application, thickness of the sealing layer) is preferably substantially constant. This can further prevent deterioration of tire uniformity and produce a self-repairing tire with better weight balance.

[0167] Here, in this specification, the thickness being substantially constant means that the thickness fluctuation is controlled to be 90 to 110% (preferably 95 to 105%, more preferably 98 to 102%, and even more preferably 99 to 101%).

[0168] Because nozzle clogging is less likely, operational stability is excellent, and better results can be achieved, it is preferred to use a sealing material in a roughly cord-like shape, and more preferably to apply the sealing material in a roughly cord-like shape to the inner circumference of the tire in a spiral shape. However, a sealing material other than a roughly cord-like shape may be applied by spraying the sealing material onto the inner circumference of the tire.

[0169] When using a substantially rope-shaped sealing material, the width of the sealing material (the width of the sealing material after application, Figure 4 The length (represented by W in FIG) is not particularly limited, but is preferably 0.8 mm or greater, more preferably 1.3 mm or greater, and even more preferably 1.5 mm or greater, for the sake of achieving better results. Furthermore, the width of the sealing material is preferably 18 mm or less, more preferably 13 mm or less, even more preferably 9.0 mm or less, particularly preferably 7.0 mm or less, most preferably 6.0 mm or less, and even more preferably 5.0 mm or less.

[0170] Thickness of sealing material (thickness of sealing material after coating, thickness of sealing layer, Figure 8 The length shown by D in the figure) and the width of the sealing material (the width of the sealing material after coating, Figure 4 The ratio (thickness of the sealing material / width of the sealing material) of the sealing material (length indicated by W in FIG) is preferably 0.6 or greater, more preferably 0.7 or greater, further preferably 0.8 or greater, and particularly preferably 0.9 or greater. Furthermore, it is preferably 1.4 or less, more preferably 1.3 or less, further preferably 1.2 or less, and particularly preferably 1.1 or less. The closer this ratio is to 1.0, the more ideal the shape of the sealing material is, and the more productive it is to manufacture a self-repairing tire with high sealing performance.

[0171] The cross-sectional area of ​​the sealing material (the cross-sectional area of ​​the sealing material after coating, Figure 8 The area calculated by D×W in the figure is preferably 0.8 mm because it can obtain better results. 2 More than, more preferably 1.95mm 2 Above, more preferably 3.0mm 2 Above, particularly preferably 3.75mm 2 More than, in addition, preferably 180mm 2 Below, more preferably 104mm 2 Below, more preferably 45mm 2 Below, particularly preferably 35mm 2 Below, most preferably 25mm 2 the following.

[0172] The width of the area where the sealing material is attached (hereinafter also referred to as the width of the attached area, the width of the sealing layer, Figure 4 The length shown as 6×W, Figure 6 The length (shown as W1+6×W0) is not particularly restricted, but based on the reason that better effects can be obtained, it is preferably more than 80% of the tread contact width, more preferably more than 90%, further preferably more than 100%. In addition, it is preferably less than 120%, more preferably less than 110%.

[0173] The width of the sealant layer is preferably 85 to 115% of the width of the tire breaker layer (the length of the breaker layer in the tire width direction) in order to obtain a better effect.

[0174] In this specification, when a plurality of breaker layers are provided in a tire, the tire widthwise length of the breaker layers refers to the tire widthwise length of the breaker layer having the longest length among the plurality of breaker layers.

[0175] In this specification, the tread contact patch width is defined as follows. First, when a tire is mounted on a regular rim and inflated to a regular internal pressure, in an unloaded, normal state, and with a regular load applied, the axially outermost contact patch of the tire, when the tire contacts a flat surface at a camber angle of 0 degrees, is defined as the "contact patch edge" Te. The axial distance between these contact patches Te and Te is defined as the tread contact patch width TW. Unless otherwise specified, dimensions of various tire components are values ​​measured in this normal state.

[0176] The term "regular rim" refers to the rim specified for each tire in the standard system that includes the specifications to which the tire is based. In JATMA, this refers to the "standard rim," in TRA, it refers to the "design rim," and in ETRTO, it refers to the "measuring rim." Furthermore, the term "regular internal pressure" refers to the air pressure specified for each tire in the standard system that includes the specifications to which the tire is based. In JATMA, this refers to the "maximum air pressure," in TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and in ETRTO, it refers to the "inflation pressure." For passenger car tires, this is 180 kPa.

[0177] The "normal load" mentioned above refers to the load specified for each tire in each specification system including the specifications on which the tire is based. In JATMA, it refers to the "maximum load capacity." In TRA, it refers to the maximum value stated in the table "TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES." In ETRTO, it refers to "LOAD CAPACITY." When the tire is for a passenger car, it is a load equivalent to 88% of the above load.

[0178] The rotation speed of the tire during application of the sealant is not particularly limited, but is preferably 5 m / min or higher, more preferably 10 m / min or higher, and preferably 30 m / min or lower, more preferably 20 m / min or lower, for the purpose of obtaining better effects.

[0179] By using a non-contact displacement sensor, the risk of failure caused by the adhesion of sealing materials to the sensor can be reduced. As the non-contact displacement sensor used, there is no particular limitation as long as it is a non-contact displacement sensor that can measure the distance between the inner circumference of the tire and the front end of the nozzle. For example, laser sensors, light sensors, electrostatic capacitance sensors, etc. can be mentioned. These sensors can be used alone, or two or more types can be used in combination. Among them, based on the viewpoint of measuring rubber, laser sensors and light sensors are preferred, and laser sensors are more preferred. When using a laser sensor, by irradiating the inner circumference of the tire with laser, the distance between the inner circumference of the tire and the front end of the laser sensor is measured based on the reflection of the laser, and the distance between the front end of the laser sensor and the front end of the nozzle is subtracted from this value. The distance between the inner circumference of the tire and the front end of the nozzle can be calculated.

[0180] The position of the non-contact displacement sensor is not particularly limited as long as it can measure the distance between the inner peripheral surface of the tire and the nozzle tip before the sealant is applied. It is preferably installed on the nozzle, and more preferably placed at a position where the sealant is not attached.

[0181] Furthermore, there are no particular limitations on the number, size, etc. of the non-contact displacement sensors.

[0182] Since non-contact displacement sensors are sensitive to heat, they are preferably protected with a heat-insulating material or cooled with air to prevent the heat from the high-temperature sealing material ejected from the nozzle. This can improve the durability of the sensor.

[0183] In the description of the first embodiment, an example in which the tire moves while the nozzle does not move is described as the movement in the width direction and the radial direction of the tire. However, the tire may not move while the nozzle moves, or both the tire and the nozzle may move.

[0184] Furthermore, the rotary drive device preferably includes a means for expanding the width of the tire's bead portion. This widening of the tire's bead portion facilitates application of the sealant to the tire. In particular, after the tire is mounted on the rotary drive device, the nozzle can be introduced near the tire's inner circumference simply by moving the nozzle parallel to the tire, facilitating control and improving productivity.

[0185] As a means for expanding the width of the tire bead portion, as long as the width of the tire bead portion can be expanded, there is no particular limitation, and examples include a device using two groups of multiple (preferably two) rollers whose positions remain unchanged, a mechanism that moves respectively along the tire width direction, etc. This device is placed into the tire from both sides of the tire opening to widen the width of the tire bead portion.

[0186] In this manufacturing method, the sealing material, mixed in a twin-screw kneading extruder or other device, and cross-linking reactions within the extruder are suppressed, is directly applied to the inner circumference of the tire. Therefore, the cross-linking reaction begins from the moment of application, providing excellent adhesion to the inner circumference of the tire. Furthermore, the cross-linking reaction proceeds more efficiently, enabling the production of a self-repairing tire with high sealing properties. Consequently, further cross-linking of the self-repairing tire coated with the sealing material is not required, resulting in excellent productivity.

[0187] Furthermore, if necessary, a cross-linking step of further cross-linking the self-repairing tire coated with the sealant may be performed.

[0188] In the cross-linking process, the self-repairing tire is preferably heated. In this way, the cross-linking speed of the sealing material can be increased, the cross-linking reaction can be carried out better, and the self-repairing tire can be manufactured with better productivity. There is no particular limitation on the heating method, and a known method can be used, but a method using an oven is preferred. In the cross-linking process, for example, the self-repairing tire can be placed in an oven at 70°C to 190°C (preferably 150°C to 190°C) for 2 to 15 minutes. In addition, since even a sealing material that is easy to flow immediately after application can be prevented from flowing and the cross-linking reaction can be carried out without deteriorating the uniformity, it is preferred to rotate the tire in the circumferential direction of the tire during cross-linking. The rotation speed is preferably 300 to 1000 rpm. Specifically, for example, as an oven, an oven with a rotating mechanism can be used.

[0189] Furthermore, even when a separate cross-linking step is not performed, it is preferable to rotate the tire circumferentially until the cross-linking reaction of the sealant is complete. This prevents the sealant from flowing even immediately after application, allowing the cross-linking reaction to proceed without deteriorating its uniformity. The rotational speed is the same as in the cross-linking step.

[0190] In order to increase the cross-linking speed of the sealing material, it is preferred to preheat the tire before applying the sealing material. In this way, self-repairing tires can be manufactured with better productivity. The preheating temperature of the tire is preferably above 40°C, more preferably above 50°C, and preferably below 100°C, more preferably below 70°C. By setting the preheating temperature of the tire within the above range, the cross-linking reaction starts well from the time of coating, the cross-linking reaction proceeds more appropriately, and a self-repairing tire with high sealing performance can be manufactured. In addition, by setting the preheating temperature of the tire within the above range, since a cross-linking process is not required, self-repairing tires can be manufactured with good productivity.

[0191] Continuous kneading machines (particularly twin-screw kneading extruders) generally operate continuously. On the other hand, when manufacturing self-repairing tires, when coating one tire is completed, the tire needs to be replaced. In this case, in order to suppress the decline in productivity while manufacturing higher-quality self-repairing tires, the following methods (1) and (2) can be used. Since method (1) has the disadvantage of reduced quality and method (2) has the disadvantage of increased cost, it is appropriate to use them according to the situation.

[0192] (1) Control the supply of sealing material to the inner surface of the tire by operating and stopping the continuous mixer and all supply devices at the same time

[0193] That is, when coating of one tire is completed, the continuous kneading machine and all supply devices are stopped simultaneously, the tire is replaced (preferably within 1 minute), the continuous kneading machine and all supply devices are started simultaneously, and coating of the tire is restarted. By quickly replacing the tire (preferably within 1 minute), it is possible to suppress the decline in quality.

[0194] (2) By keeping the continuous mixer and all supply devices in operation, the flow path is switched to control the supply of the sealing material to the inner peripheral surface of the tire.

[0195] Specifically, a separate flow path is pre-installed in the continuous kneading machine from the nozzle that feeds directly to the inner circumference of the tire. When coating a tire is completed, the prepared sealing material is discharged through the separate flow path until the tire is replaced. This method allows self-repairing tires to be manufactured while the continuous kneading machine and all feeding devices remain operational, resulting in higher-quality self-repairing tires.

[0196] The carcass cord used in the self-repairing tire is not particularly limited, and examples thereof include fiber cords and steel cords. Steel cords are preferred. Steel cords formed from hard steel wire rods as specified in JIS G3506 are particularly desirable. In self-repairing tires, using high-strength steel cords instead of conventional fiber cords as the carcass cord significantly improves sidewall cut resistance (resistance to sidewall cuts caused by, for example, riding on curbs), further improving the puncture resistance of the entire tire, including the sidewalls.

[0197] The structure of the steel cord is not particularly limited, and examples include single-twisted steel cords with a 1×n structure, layer-twisted steel cords with a k+m structure, bundle-twisted steel cords with a 1×n structure, and multi-twisted steel cords with an m×n structure. A single-twisted steel cord with a 1×n structure refers to a single-layer twisted steel cord made by twisting n filaments together. A layer-twisted steel cord with a k+m structure refers to a steel cord with two layers of twist directions and lay lengths, with k filaments in the inner layer and m filaments in the outer layer. A bundle-twisted steel cord with a 1×n structure refers to a bundle-twisted steel cord made by twisting n filaments together. An m×n multi-twisted steel cord refers to a multi-twisted steel cord made by twisting m strands of n filaments together. n is an integer from 1 to 27, k is an integer from 1 to 10, and m is an integer from 1 to 3.

[0198] The lay pitch of the steel cord is preferably 13 mm or less, more preferably 11 mm or less, and is preferably 5 mm or more, more preferably 7 mm or more.

[0199] The steel cord preferably includes at least one spirally shaped filament. Such a filament can provide a large gap in the steel cord, thereby improving rubber permeability while maintaining elongation under low loads and preventing poor forming during vulcanization.

[0200] In order to improve the initial adhesion to the rubber composition, the surface of the steel cord is preferably plated with brass, Zn, or the like.

[0201] The elongation of the steel cord under a load of 50 N is preferably 0.5 to 1.5%, more preferably 0.7% or more, and more preferably 1.3% or less.

[0202] The density (ends) of the steel cord is preferably 20 to 50 (ends / 5 cm).

[0203] <Second embodiment>

[0204] If the method of the first embodiment alone is used, it can sometimes be difficult to apply the sealant to the inner circumference of the tire when the sealant is in a roughly string-like shape. In particular, the sealant is easily peeled off at the beginning of application. A second embodiment is characterized in that, in the above-mentioned method for manufacturing a self-repairing tire, the distance between the inner circumference of the tire and the nozzle tip is set to a distance d1. After applying the sealant, the distance is then set to a distance d2 greater than d1, and the sealant is applied. This facilitates the manufacture of a self-repairing tire having the following characteristics: by reducing the distance between the inner circumference of the tire and the nozzle tip at the beginning of application, the width of the sealant corresponding to the beginning of application is increased. At least on the inner circumference of the tire corresponding to the tread portion, the adhesive, roughly string-like sealant is continuously applied in a spiral pattern, with at least one of the longitudinal ends of the sealant having a width greater than that of adjacent longitudinal portions. In this self-repairing tire, by increasing the width of the sealant corresponding to the beginning of application, the bonding strength in this portion is improved, preventing peeling of the sealant in this portion.

[0205] In the description of the second embodiment, only the points different from the first embodiment will be mainly described, and description of the contents overlapping with the first embodiment will be omitted.

[0206] Figure 5 It is composed Figure 1 The enlarged view of the nozzle tip of the coating device shown is as follows: (a) shows the state immediately after the sealing material is applied, and (b) shows the state after a predetermined time has passed.

[0207] Figure 5It shows a cross-section obtained by cutting a part of the tire 10 in a plane including the tire circumferential direction and the radial direction. In Figure 5 , the X direction is the width direction (axial direction) of the tire, the Y direction is the circumferential direction of the tire, and the Z direction is the radial direction of the tire.

[0208] In the second embodiment, first, the tire 10 formed in the vulcanization process is set on the rotary drive device, and the nozzle 30 is inserted into the inside of the tire 10. Then, as Figure 1 and Figure 5 shown, while rotating the tire 10 and moving the tire 10 in the width direction, the sealing material 20 is continuously applied to the inner peripheral surface 11 of the tire 10 by discharging the sealing material 20 from the nozzle 30. The movement of the tire 10 in the width direction is performed, for example, along the contour shape of the inner peripheral surface 11 of the tire 10 input in advance.

[0209] Since the sealing material 20 has adhesiveness and is substantially in the shape of a rope, it can be continuously spirally attached to the inner peripheral surface 11 of the tire 10 corresponding to the tread portion.

[0210] At this time, within a predetermined time period from the start of attachment, as Figure 5 (a) shown, the distance between the inner peripheral surface 11 of the tire 10 and the front end 31 of the nozzle 30 is set to a distance d1, and the sealing material 20 is attached. Then, after the predetermined time has elapsed, as Figure 5 (b) shown, by moving the tire 10 in the radial direction, the above-mentioned interval is changed to a distance d2 greater than the distance d1, and the sealing material 20 is attached.

[0211] In addition, before the attachment of the sealing material ends, the above-mentioned interval can be changed back from the distance d2 to the distance d1, but from the viewpoints of manufacturing efficiency and tire weight balance, it is preferably the distance d2 until the attachment of the sealing material ends.

[0212] Furthermore, although it is preferably to keep the value of the distance d1 fixed within a predetermined time period from the start of attachment and keep the value of the distance d2 fixed after the predetermined time has elapsed, as long as the relationship d1 < d2 is satisfied, the values of the distance d1 and d2 do not have to be fixed.

[0213] The value of the distance d1 is not particularly limited, and for the reason that better effects can be obtained, it is preferably 0.3 mm or more, more preferably 0.5 mm or more, and the value of the distance d1 is preferably 2 mm or less, more preferably 1 mm or less.

[0214] The value of the distance d2 is not particularly limited, but is preferably 0.3 mm or more, more preferably 1 mm or more, and preferably 3 mm or less, more preferably 2 mm or less, for the purpose of obtaining better effects. The distance d2 is preferably the same as the adjusted interval d0.

[0215] In this specification, the distances d1 and d2 between the tire inner circumferential surface and the nozzle tip refer to the distances between the tire inner circumferential surface and the nozzle tip in the tire radial direction.

[0216] The rotation speed of the tire when attaching the sealant is not particularly limited, but is preferably 5 m / min or higher, more preferably 10 m / min or higher, and preferably 30 m / min or lower, more preferably 20 m / min or lower, for the purpose of obtaining better effects.

[0217] Through the above steps, the self-repairing tire of the second embodiment can be manufactured.

[0218] Figure 6 This is a schematic explanatory diagram of an example of a sealant attached to a self-repairing tire according to the second embodiment.

[0219] A roughly rope-shaped sealing material 20 is wound around the circumference of the tire and continuously applied to it in a spiral shape. Furthermore, one end of the sealing material 20 in the longitudinal direction is a width portion 21 that is wider than the width of the adjacent portion in the longitudinal direction. This width portion 21 corresponds to the starting point of the sealing material application.

[0220] The width of the width portion of the sealing material (the width of the width portion of the sealing material after coating, Figure 6 The length shown in W1 in the figure is not particularly limited, but the width other than the width portion ( Figure 6 The width of the width portion of the sealing material is preferably 210% or less, more preferably 180% or less, and further preferably 160% or less of the width other than the width portion.

[0221] The width of the width portion of the sealing material is preferably substantially constant in the longitudinal direction, but may vary in some areas. For example, the width portion may be configured such that it is widest at the beginning of attachment and gradually narrows along the longitudinal direction. In this specification, "substantially constant width" means that the width fluctuation is controlled to be 90-110% (preferably 97-103%, more preferably 98-102%, and even more preferably 99-101%).

[0222] The length of the width of the sealing material (the length of the width of the sealing material after coating, Figure 6 The length (L1) is not particularly limited, but is preferably less than 650 mm, more preferably less than 500 mm, further preferably less than 350 mm, and particularly preferably less than 200 mm for better results. The width of the sealing material is preferably as short as possible, but considering the distance between the inner circumference of the tire and the nozzle tip, the upper limit is approximately 10 mm.

[0223] The width of the sealing material other than the width portion (the width of the sealing material other than the width portion after coating, Figure 6 The length (indicated by W0) is not particularly limited, but is preferably 0.8 mm or more, more preferably 1.3 mm or more, and even more preferably 1.5 mm or more, for the sake of obtaining better effects. Furthermore, it is preferably 18 mm or less, more preferably 13 mm or less, even more preferably 9.0 mm or less, particularly preferably 7.0 mm or less, most preferably 6.0 mm or less, and even more preferably 5.0 mm or less. W0 is preferably the same as W described above.

[0224] The width of the sealing material other than the width portion is preferably substantially constant in the longitudinal direction, but may be substantially non-constant in some places.

[0225] The width of the area where the sealing material is attached (hereinafter also referred to as the width of the attached area, the width of the sealing layer, Figure 6 The length (expressed as W1+6×W0) is not particularly limited, but is preferably more than 80% of the tread contact width, more preferably more than 90%, and further preferably more than 100% based on the reason of obtaining better effect. In addition, it is preferably less than 120%, and more preferably less than 110%.

[0226] The width of the sealant layer is preferably 85 to 115% of the width of the tire breaker layer (the length of the breaker layer in the tire width direction) in order to obtain a better effect.

[0227] In the self-repairing tire of the second embodiment, the sealant is preferably applied without overlapping in the width direction, and more preferably applied seamlessly.

[0228] In the self-repairing tire of the second embodiment, the other end portion of the sealant in the longitudinal direction (the end portion corresponding to the attachment end portion) may be a wider portion having a width greater than that of an adjacent portion in the longitudinal direction.

[0229] Thickness of sealing material (thickness of sealing material after coating, thickness of sealing layer, Figure 8The length (shown as D in FIG) is not particularly limited, but is preferably 1.0 mm or more, more preferably 1.5 mm or more, further preferably 2.0 mm or more, and particularly preferably 2.5 mm or more. In addition, it is preferably 10 mm or less, more preferably 8.0 mm or less, and further preferably 5.0 mm or less, for the purpose of obtaining better effects.

[0230] The thickness of the sealing material (thickness of the sealing material after application, thickness of the sealing layer) is preferably substantially constant. This can further prevent deterioration of tire uniformity and produce a self-repairing tire with better weight balance.

[0231] Thickness of sealing material (thickness of sealing material after coating, thickness of sealing layer, Figure 8 The length shown by D in the figure) and the width of the sealing material other than the width of the width portion (the width of the sealing material other than the width of the width portion after coating, Figure 6 The ratio (thickness of the sealing material / width of the sealing material excluding the width portion) of the sealing material to the length (shown as W0 in FIG) is preferably 0.6 or greater, more preferably 0.7 or greater, even more preferably 0.8 or greater, and particularly preferably 0.9 or greater. Furthermore, it is preferably 1.4 or less, more preferably 1.3 or less, even more preferably 1.2 or less, and particularly preferably 1.1 or less. The closer this ratio is to 1.0, the more ideal the shape of the sealing material becomes, allowing for more efficient production of self-repairing tires with high sealing properties.

[0232] The cross-sectional area of ​​the sealing material (the cross-sectional area of ​​the sealing material after coating, Figure 8 The area calculated by D×W in the figure is preferably 0.8 mm because it can obtain better results. 2 More than, more preferably 1.95mm 2 Above, more preferably 3.0mm 2 Above, particularly preferably 3.75mm 2 More than, in addition, preferably 180mm 2 Below, more preferably 104mm 2 Below, more preferably 45mm 2 Below, particularly preferably 35mm 2 Below, most preferably 25mm 2 the following.

[0233] In the second embodiment, even if the viscosity of the sealing material is within the above range, especially even when the viscosity is high, by widening the width of the sealing material corresponding to the attachment start portion, the bonding force in this portion can be improved and peeling of the sealing material in this portion can be prevented.

[0234] The self-repairing tire of the second embodiment is preferably manufactured by the above-mentioned manufacturing method, but may be manufactured by any other appropriate manufacturing method as long as at least one end portion of the sealant can be formed into a wide portion.

[0235] The above description, especially in the description of the first embodiment, describes the case of using a non-contact displacement sensor when applying sealing material to the inner circumference of the tire. However, it is possible to control the movement of the nozzle and / or the tire according to pre-input coordinate values ​​to apply sealing material to the inner circumference of the tire without performing measurements based on the non-contact displacement sensor.

[0236] The above-described method and other methods can produce a self-repairing tire having a sealing layer made from the aforementioned rubber composition for use as a sealant, located radially inward of the inner liner. Because the sealing layer of this pneumatic tire is made from the aforementioned rubber composition for use as a sealant, it exhibits excellent failure characteristics, maintains good sealing performance even after aging, and suppresses changes in failure characteristics over time.

[0237] The sealing layer is preferably composed of a substantially cord-shaped sealing material continuously spirally arranged along the inner circumferential surface of the tire. More preferably, the spirally arranged substantially cord-shaped sealing materials are seamlessly arranged without overlapping each other in the width direction.

[0238] The self-repairing tire structure described above has excellent sealing performance because it has a sealing layer (composed of a substantially cord-like sealing material continuously spirally arranged along the inner circumference of the tire) uniformly distributed along the tire's circumference and width (particularly the circumferential direction) on the tire's inner circumference. Furthermore, the sealing material prevents the tire from losing balance, thus reducing deterioration in tire uniformity.

[0239] Furthermore, by configuring the sealant layer produced using the sealant rubber composition as described above, a higher effect tends to be achieved. This is presumably because the sealant layer has a uniform thickness, which leads to a higher effect.

[0240] The sealant layer having the above-mentioned structure can be produced, for example, by continuously and spirally applying a substantially rope-shaped sealant to the inner peripheral surface of the tire.

[0241] The complex elastic modulus G of the sealing layer measured at 100°C according to ISO13145 (2012) is * Preferably it is 0.75 to 3.50 kPa. *It is more preferably 1.00 or more, further preferably 1.25 or more, particularly preferably 1.50 or more, most preferably 1.75 or more, still more preferably 2.00 or more, further most preferably 2.20 or more, and particularly most preferably 2.30 or more. In addition, it is more preferably 3.25 kPa or less, further preferably 3.00 kPa or less, particularly preferably 2.80 kPa or less, and most preferably 2.60 kPa or less. When the complex elastic modulus is within the above range, there is a tendency to obtain better effects. In addition, in this specification, the complex elastic modulus G * It is a value measured at 100° C. in accordance with ISO 13145 (2012), specifically, a value measured by the method of Examples.

[0242] In the sealing layer, in order to make the complex elastic modulus G * The sealant can be produced using the rubber composition described above within the above range. In particular, for butyl rubber, a specific amount of a thiourea crosslinking agent represented by formula (I), a specific amount of a thiazole vulcanization accelerator and / or a thiuram vulcanization accelerator, and a specific amount of a liquid polymer can be added.

[0243] More specifically, a specific amount of a thiourea crosslinking agent represented by the above formula (I), a specific amount of a thiazole vulcanization accelerator and / or a thiuram vulcanization accelerator, and a specific amount of liquid polybutene may be added to the butyl rubber.

[0244] The tires described above can be suitably used as tires for passenger cars, large passenger cars, large SUVs, truck / buses, two-wheeled vehicles, racing tires, winter tires (studless tires, snow tires, stud tires), all-season tires, run-flat tires, aircraft tires, mining tires, and the like.

[0245] [Example]

[0246] The present invention will be described in detail based on Examples, but the present invention is not limited to these Examples.

[0247] Various chemicals used in the examples are described below.

[0248] Butyl rubber: Bromobutyl 2255 (manufactured by ExxonMobil Corporation, Mooney viscosity ML1+8 at 125° C. = 46, halogen content: 2.0% by mass)

[0249] Carbon black: Vulcan 6 (manufactured by MahaChem, N220)

[0250] Liquid polybutene: Nippon Seki Polybutene HV1900 (manufactured by JXTG Energy Corporation, kinematic viscosity at 40°C: 160,000 cSt, kinematic viscosity at 100°C: 3,710 cSt, number average molecular weight: 2,900)

[0251] Zinc oxide: Zinc oxide No. 2 (manufactured by Mitsui Mining & Smelting Co., Ltd.)

[0252] Thiuram accelerator: Accel TBZT (manufactured by Kawaguchi Chemical Industry Co., Ltd., tetrabenzylthiuram disulfide (TBzTD))

[0253] Thiazole accelerator: Accel DM (manufactured by Kawaguchi Chemical Industry Co., Ltd., dibenzothiazolyl disulfide (MBTS))

[0254] Peroxide: BENZOXE (manufactured by Kawaguchi Pharmaceutical Co., Ltd., benzoyl peroxide)

[0255] Quinone crosslinker: VULNOC GM-P (manufactured by Ouchi Shinko Chemical Co., Ltd., p-quinone dioxime)

[0256] Thiourea crosslinking agent 1: Sanceler TMU (manufactured by Sanshin Chemical Co., Ltd., trimethylthiourea (a compound represented by the following formula (2)))

[0257]

[0258] Thiourea crosslinking agent 2: Sanceler EUR (manufactured by Sanshin Chemical Co., Ltd., N,N'-diethylthiourea (a compound represented by the following formula (1)))

[0259]

[0260] <Manufacturing of Self-Repairing Tires>

[0261] According to the formulation shown in Table 1, a sealing material was prepared by kneading at 170° C. for 60 minutes using a 3 L kneading mixer.

[0262] Next, from a nozzle directly connected to the discharge port of the mixer and with the tip set on the inner surface of the tire, the prepared sealing material (temperature 170°C, viscosity 35000 Pa·s (40°C), roughly in the shape of a rope, thickness 3mm, width 4mm) was sequentially discharged onto the inner surface of the tire (205 / 55R16, preheated temperature: 40°C) rotating in the circumferential direction. Figures 1 to 4The sealant was continuously applied in a spiral pattern to the inner circumference of the tire, achieving a thickness of 3 mm and an adhesion area width of 180 mm to form a sealing layer, thereby producing a self-repairing tire. The viscosity of the sealant was measured at 40°C using a rotational viscometer in accordance with JIS K 6833.

[0263] Here, the cross-linking and curing reaction proceeds by the heat generated during kneading.

[0264] The following evaluations were performed using the obtained test tires. The results are shown in Table 1.

[0265] <Heat aging test>

[0266] The obtained test tires were stored at 60° C. for 20 days to obtain heat-aged test tires.

[0267] <Dynamic complex elastic modulus>

[0268] A test piece was cut from the sealant layer of the self-repairing tire (new, after heat aging). The dynamic complex elastic modulus G of the test piece was measured at 100°C using an RPA manufactured by Alpha Technology in accordance with ISO 13145 (2012). * .

[0269] In addition, based on the new product and the G after thermal aging * , calculate the change ratio (G after thermal aging * The closer the change ratio is to 100%, the more the temporal change in the destructive characteristics can be suppressed. When the change ratio is 150% or less, it is judged that the temporal change in the destructive characteristics can be suppressed.

[0270] When the complex elastic modulus G * (New) When the value is 0.75 kPa or above, the fracture characteristics are judged to be excellent. In particular, when the complex elastic modulus G * (New product) When the pressure is 0.80 kPa or more, the destructive characteristics are judged to be more excellent.

[0271] <Airtightness>

[0272] The self-repairing tires (new) were left to deteriorate at 60°C for 10 days, and then 100 tires were placed in a constant temperature room at -25°C. The airtightness success rate when driving and pulling out a 30mm long nail. A higher airtightness success rate indicates better sealing performance after aging, and greater suppression of deterioration in sealing performance over time.

[0273] <Shape Retention>

[0274] The self-repairing tires (new) were left to stand at 60° C. for 10 days to accelerate degradation and were then evaluated. Good appearance products showing seal shape retention were rated as 0, while bad appearance products were rated as ×.

[0275] [Table 1]

[0276]

[0277] As can be seen from Table 1, the examples containing 0.5 to 3 parts by mass of a thiourea crosslinking agent represented by the above formula (I), 1 to 10 parts by mass of a thiazole-based vulcanization accelerator and / or a thiuram-based vulcanization accelerator, and 100 to 300 parts by mass of a liquid polymer, relative to 100 parts by mass of the butyl-based rubber, exhibited excellent fracture characteristics and good sealing properties even after aging.

Claims

1. A rubber composition for a sealing material, characterized in that: The rubber composition contains 0.5 to 3 parts by mass of a thiourea crosslinking agent represented by the following formula (I), 1 to 10 parts by mass of a thiazole vulcanization accelerator and / or a thiuram vulcanization accelerator, and 100 to 300 parts by mass of a liquid polymer, relative to 100 parts by mass of the butyl rubber: In formula (I), R 1 ~R 4 are the same or different and represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; R 1 With R 3 , or R 1 With R 4 , or R 2 With R 3 , or R 2 With R 4 A ring structure may or may not be formed.

2. The rubber composition for a sealant according to claim 1, wherein The thiourea cross-linking agent is any one of the following compounds:

3. The rubber composition for a sealant according to claim 1 or 2, wherein The liquid polymer is liquid polybutene.

4. The rubber composition for a sealant according to claim 1 or 2, wherein The kinematic viscosity of the liquid polymer measured at 100° C. according to ASTM D445 is 500 to 6000 cSt.

5. The rubber composition for a sealant according to claim 1 or 2, wherein The content of the organic peroxide is 1 part by mass or less relative to 100 parts by mass of the butyl rubber.

6. A pneumatic tire, characterized in that: The present invention comprises a sealant layer produced using the rubber composition according to any one of claims 1 to 5.

7. The pneumatic tire according to claim 6, wherein: The sealing layer has a complex elastic modulus G* measured at 100° C. according to ISO 13145 and is 0.75 to 3.50 kPa.

Images